1. Field of the Invention
The present invention relates to an improvement made to machines capable of producing cabled yarns, textile elements of great length obtained by twisting together at least two elementary threads.
It concerns, more particularly, an improvement made to machines of the type described in French Patent Application No. 84 08 975 (Publication No. 2 565 261).
2. Related Art Statement
In general, and as can be seen from the accompanying FIG. 1 which is a reproduction of the FIG. 1 illustrating the abovementioned patent, a cabling machine consists of a plurality of identical work stations disposed side by side, each station comprising a unit similar to a double-twist unwinding spindle (DT unit) which enables the two elementary threads (1, 2) to be united by twisting. The thread (1) taken from a feed source (not shown) arrives at the bottom end of the hollow spindle (3) of the DT unit and passes through a radial channel pierced in a rotating plate (3a) on said spindle. Because of the rotation of the spindle the thread is subjected to a false twist and forms a balloon (1a) which surrounds the bowl (3b) of the spindle (3) of the DT unit. A spool (4) of the second thread (2) is disposed inside the bowl (3a). This second thread (2) passes through a braking device (6) carried on the lid (3c) of the bowl (3b). The threads (1) and (2) are united by twisting by means of a unit given the general reference (7) and commonly called a "cabling head" or "regulator". The invention relates more particularly to this unit and will be seen in greater detail in the remainder of the description. After the two threads have been joined together by twisting at the outlet of the cabling head (7), the cabled yarn (8) formed passes onto a device (9) preventing the twist from rising and then, optionally, after passing around a direction-change guide (10), it is wound in a conventional system given the general reference (11).
As previously stated, the invention relates more particularly to an improvement made to the cabling head or regulator (7) contained in an installation of this kind.
Generally speaking, cabling heads (7) of this kind have up to the present time consisted essentially of a rotating unit mounted in a top bearing (12) in line with the spindle axis. This rotating unit comprises essentially two pulleys (13, 14) disposed on the same axis transverse to the axis of the spindle (3) and angularly fixed relative to one another. The threads (1, 2) wind around these pulleys (13, 14) and are then united at the actual cabling point (15), thereupon passing into an axial channel in the rotating unit (7) for delivery to the system (9) preventing the twist from rising. Rotating-pulley cabling heads of this kind have been known for a very long time, and are described in particular in French Patent No. 1 208 273. It is well known that the rotational driving of the cabling head can be derived either from the outer thread (1) forming the balloon (1a), or optionally from an individual motor permitting perfect synchronism.
In cases where the rotational driving of the cabling head is derived from the ballooning thread (1a), one of the problems that arise is starting from the working position, because in this phase of the operation, it is necessary that the tension of the balloon (1a) is sufficient to provide a driving torque capable of overcoming the resisting torque of the regulator (or cabling head) due to inertia and residual friction. In the opposite case, the regulator will, in fact, immediately lag behind, thus giving rise to a reduction of the driving torque, which may even be eliminated when the lag reaches 180.degree. C., thus immediately causing a break.